Data Interfaces And Data Transfer Across The Link; Simplex And Asymmetric Operation - Comtech EF Data CDM-700 Installation And Operation Manual

CDM-700 High Speed Satellite Modem
Functional Description
3.2.1

Data Interfaces And Data Transfer Across The Link

Data into a port (a port is a Tx / Rx pair) at one end of the link is transferred to the same port at
the other end. If HSSI is plugged into Slot 1 then a HSSI module is plugged into Slot 1 at the
other end of the link for proper data transfer. Transfer of data between the Gigabit Ethernet
module in Slot 1at the near end to the HSSI module in Slot 1 at the distant end is not allowed.
When considering 1:N redundancy refer to the CRS-300 manual to see how it is possible to mix
some data interfaces within the same switch for a cost effective solution.
3.2.2

Simplex and Asymmetric Operation

The CDM-700 is available in a full duplex or Rx only configuration, and mixing of 70/140 MHz
and L-Band in the same chassis is not allowed. Most of the interfaces allow turning off the Tx or
Rx side of the data interface, and this configures the disabled port to 0 Mbps. The composite data
rate must lie within range of the allowable range for the chosen modulation and code rate.
Asymmetric operation is allowed on most interfaces. The OC-3 / STM-1 is an exception, and it
operates only at 155.52 Mbps. Asymmetric operation of the G.703 is also possible, although
seldom used. Here is an example of Tx (E3) and Rx (DS3):
CDM-700 At Near End
Port 1
Tx
E3 Disable
Notice the in this example data is transferred across the link to the same port and the same slot.
Asymmetric operation of the Gigabit Ethernet and HSSI interfaces is also allowed and simpler to
configure.
Slot 1
Port 2
Rx Tx
Disable
CDM-700 At Distant End
Port 1
Rx Tx
DS3 Disable
3–4
Revision 5
MN/CDM700.IOM
Slot 1
Port 2
Rx Tx
E3 DS3 Disable
Rx